Finance Minister Nirmala Sitharaman today announced a Rs 70,000 crore boost to the housing and construction sectors that have been affected by the coronavirus outbreak and lockdown, by extending an interest subsidy scheme meant to help middle class families build or purchase a house.Ms Sitharaman, unveiling the second tranche of Prime Minister Narendra Modi’s Rs 20 lakh crore stimulus package for a coronavirus-hit economy, said a credit-linked subsidy scheme for middle-income groups that had been operationalised in May 2017 and expired on March 31 would be extended by 12 months to March 2021.